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Патент USA US2134896

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Now 1, 1938.
B. n. H. TELLEGEN ET AL
2,134,396
ELECTRON DI SCZ‘IARGE EE'V'I
Filed April 19, 1338
’
BERNARDUS
BY
INVENTOR.
D. H. TELLEGEN
MARC ZIEGLER
We -
A TTORNEY.
Patented Nov. 1, 1938
2,134,896
UNITED STATES PATENT OFFICE
2,134,896
‘ELECTRON DISCHARGE DEVICE
Bernardus Dominicus Hubertus Tellegen and
Marc Ziegler, Eindhoven, Netherlands, assign
ors to N. V. Philips’ Gloeilampenfabrieken,
‘Eindhoven, Netherlands
Application April 19, 1938, Serial No. 202,820
In Germany March 17, 1937
3 Claims. (Cl. 250-275)
This invention relates to electron discharge tube the invention permits the distribution hiss
tubes to be used in a circuit arrangement for the factor to be made smaller than 1/8. we have
ampli?cation or frequency transformation of found, however, that in frequency transformation
electrical oscillations, in which at least the ?rst arrangements, wherein the incoming oscillations
tube comprises two or more electrodes at a posi
and the locally produced oscillations are supplied
tive potential.
to different grids in a mixing tube, this limit must
As is well known, ‘biasing occurs in radio ar
be given a higher value, that is a distribution hiss
rangements from the coupling elements and from factor of l/2.
the tubes and more particularly from those cou
pling elements and tubes wherein the incoming
‘signal has only a small amplitude, for instance,
in the high frequency part of a radio receiving
arrangement.
The principal object ‘of our invention is to pro
The invention will be more clearly understood
by reference to the following calculation.
issuing entirely independently of each other from
a hot cathode, is represented by the Well-known
expression for the shot effect:
' vide an electron discharge device particularly
suitable for ampli?cation or frequency transfor
mation in which tube noise and hiss is reduced.
The novel features which we believe to be char
acteristic of our invention are set forth with par
)
ticularity in the appended claims, but the inven
tion itself will best be understood by reference to
the following description taken in connection with
the accompanying drawing in which Figure 1 is
a schematic diagram of an electron discharge
device made according to our invention and Fig
ure 21s a modi?cation of the electron discharge
device shown in Figure 1 and employing our in
vention.
Extensive experiments indicate, especially in
5
connection with hissing caused in the tube, par
ticularly when used at high frequencies, that by
making use of an arrangement of an electron
discharge device according to the present inven
tion hissing can be substantially reduced.
3;,
In a circuit arrangement for the ampli?cation
or frequency transformation of electrical oscil
lations wherein at least the ?rst tube comprises
two or more electrodes having a positive poten
tial, the distribution hiss factor of the currents
40 and voltages used in the apparatus is, according
to the invention, made smaller than l/8.
The fact that a screen grid tube involves more
hissing than a triode was found to be due to
accidental variations in the ratio between the
v-a 5; screen grid current and the anode current.
According to the invention the oscillations of
the anode current in a screen grid tube are re
U
duced to a minimum by rendering ‘the screen grid
current or the variations of the ratio between the
screen grid current and the anode current to be
as small as possible.
>
In an amplifying arrangement or in a frequency
transformation arrangement, in which the incom
ing oscillations and the locally produced oscilla
"50 tions are supplied to the same grid of a mixing
The i
value of the oscillations of the stream of electrons
3:5
(1)
wherein
T2:
the contribution from a definite frequency band
to the average square variations of the emission;
17.
average emission current;
Cztwice the charge of the electron times the
width of the frequency band in question.
This formula holds good for the current varia
tions of a saturated diode, in which all of the
electrons issuing from the cathode pass to the
anode.
In cases wherein a potential minimum
occurs due to the space‘ charge in the vicinity of
the cathode, so that part of the electrons returns
to the cathode, a certain regularity evolves in the
stream of electrons leaving the space charge, so
that the variations of this current are smaller
than the pure accidental variations which are ex
35
pressed by the equation:
ii=F?.C.I,,
(2)
wherein the “hiss factor” Fi is smaller than 1.
Generally the hiss factor is to be understood
to mean the ratio between the average square
variations of a stream of electrons which pass en
tirely independently of one another and which
stream has a uniform value on an average.
The regularity of the stream of electrons leav
ing a space charge may ‘in practice be such that
the hiss factor Pi is smaller than 0.05. In elec
tron tubes, wherein the anode current forms only
part of the total cathode current, the anode cur
rent may relatively and absolutely carry more 50
variations than the cathode current due to the
fact that the division of the total number of elec
trons in anode electrons and remaining electrons
is accidental to a certain extent which involves
“distribution variations”.
2
2,134,898
current correspond to the sum of the independ
ent contributions of
Consequently the hiss factor
Ff
of the anode current Ia in cases, wherein the an
ode current is smaller than the cathode current,
Ta
and
E5
must be higher than the hiss factor
Ff
Thus we have, in accordance with (2):
of the cathode current
Ti=1-C-[FiZl+aI";-I“~C-[(1— all
IT.
10
I:
For a de?nite ratio between
(4)
Now, per de?nition:
I“,
55:12.01‘;
and
so that
R
an upper limit of
F2: z+[a%]c- a)
F3
(s)
k
can be calculated by considering the electron
20 distribution as a pure calculation of probabilities.
A calculation of probabilities shows that if the
total current
T,
In an electron discharge tube having one or
20
more grids
I,,—I,,=1,
and (5) acquires the form:
were perfectly uniform,
F2:
.
I
2
-_~”_i+a
Ia+1g< 1— i)2
< 6>
( i=0),
the hiss factor of the anode current would be:
011L151
30
(3)
lie
the accident factor or being 1 if the distribution
answers to pure accident laws, and smaller than
1 if the distribution takes place in conformity
to certain geometrical laws. However, the stream
of electrons
In order to obtain a small value for
F2
2
the two members of the right hand part of (6) 30
should be small. In the ?rst place the hiss factor
of the cathode current, in the second place the
factor
H
originating from the space charge is never per
fectly uniform, so that
40
which will be called the distribution hiss factor
According to (6) it has a value
40
However, this stream may be imagined to be split
up in a, fraction
TE=F§IY
and can be determined experimentally for any
45 with complete accidental variation (hiss factor
:1) and a fraction
Ik0=(1—F:>Tk
which is perfectly uniform (hiss factor=0).
50 The part of
TH.
going to the anode, which part amounts to
E.
55
TfFkra
has a hiss factor 1, because in view of the fact
that initially complete irregularity prevails, no
60 greater disturbance can be brought into each
part due to the distribution, whilst there is
neither a mechanism providing regularity.
The portion
Z5 of 71.?)
going, to the anode which portion has a value of
76f,
k z: (1_ all‘
Ik
has a hiss factor represented by (3), viz:
aIkO—I,,O=aI,,fl,,
75
These considerations apply for an arbitrary
number of positive grids in the tube. However,
it was taken for granted that the grids had a
constant voltage. When (in a mixing tube) one
of the grids has an alternating voltage, whose
frequency is not low in comparison with the fre
quencies of the band transmitted on the anode
side, the relations inferred no longer hold good.
In contradistinction thereto it will be obvious
that if for the whole cycle of adjustments tra
versing the tube, the hiss factors, considered
statically (for which case the formulae apply)
7.,_ 2
11,0
electron discharge tube.
1;,
The total average square variations of the anode
be as favorable as possible, the hiss factor of the
tube during operation will also be as favorable as
possible. Thus, the means for keeping the hiss
factor of the anode current of a mixing tube as
low as possible correspond to those referred to
above.
'
The invention has for its purpose to make the
distribution hiss factor as small as possible and
more particularly smaller than
1A;
for am
plifying arrangements and frequency trans
formation arrangements, in which the received
oscillations and the locally produced oscilla
tions are supplied to the same grid of the ?rst
detector tube, and smaller than 1A2 for frequency
transformation arrangements in which the re
ceived oscillation and the locally produced oscil
lations are supplied to different grids of a mixing 76
3
2,134,896
tube. This can be ensured in various ways. Pri- with each other or extend in one plane.
The
screen grid 4’ forming part of the tube shown in
marily the ratio
In
Figure 2 may consist of ?at ribbon wound as a
2+2
helix or may be of plate-shaped parts if the elec
trodes are planar. The electrodes are preferably
concentricate in which case grid 3’ may be wound
as a double helical grid, that is the grid includes a
in a screen grid tube may be made as small as
possible, i. e. the screen grid current may be
reduced to a minimum. In an arrangement ac“
cording to the invention an electron discharge
10 tube may be used for this purpose, the electrode
system of which tube includes, among other elec
trodes, a screen grid and in which tube the ac
tive parts of the screen grid, seen in the direc
tion from the cathode to the anode normally to
the cathode surface, lie in the shadow of the
active parts of one or more grids arranged be
tween the cathode and the screen grid.
According to a particular form of construction
of the present invention the high frequency part
20 of a radio receiving arrangement comprises a tube
having a control grid with variable pitch, and in
which the screen grid arranged behind the con
trol grid is Wound so as to be variable substan
tially in the same manner as the control grid.
25
For solving the problem put with the invention
it is not necessary to use grids wound with a var
iable pitch, since it is also possible to use grids
known arranged one behind the other and not
wound with a variable pitch.
30
In frequency transformation arrangements in
which the local oscillations and the received os
cillations are supplied to two different grids in the
mixing tube the active parts of all grids might be
arranged in their respective shadows. However,
35 this has the objection that the control grid re
motest from the cathode has an insu?icient con
trol effect on the stream of electrons which may
involve serious di?iculties more particularly when
this grid is used as an input control grid. For
this reason it is well-nigh impossible in. such a
mixing tube to arrange all grids one behind the
other, so that the distribution hiss factor is al
ways larger than in a high frequency amplifying
arrangement or in a frequency transformation
arrangement, in which the local and received os
45
cillations are supplied to the same grid.
Another method of making the distribution
hiss factor as small as possible is to make the ac
cident factor a as small as possible.
This is
achieved when each of the current conveying
50 electrodes receives its electrons from a different
part of the space charge, which part is as inde
pendent as possible.
They may be e?ected by
means of such a construction of the screen grid
that the cathode can be imagined to consist of
55 two or more parts, substantially all the electrons
emitted by one part passing to the anode. and
substantially all of those emitted by another part
60
passing to the screen grid. For this purpose an
electric discharge tube may be used whose elec
trode system includes, inter alia, a screen grid
and in which this screen grid consists of plate
shaped parts.
,
Finally a combination of these two measures
may be used.
65
In the drawing the envelope l of a tube en
closes a cathode 2, a control grid 3, a screen grid
4 and an anode 5. As appears readily from the
drawing the tube shown in Figure 1 is provided
70 with a control grid and a screen grid both of
which are wound with a variable pitch and whose
active parts, seen in a direction from the cathode
to the anode normally to the cathode register
pair of spaced interspersed helical wires wound
in the same side rods. This permits positioning
of the outer concentric ribbon grid so that its
solid portion registers with alternate spaces be
tween the turns of the wires and the space be
tween the turns of the ribbon grid registers with
other alternate spaces between the turns of the
wire grid. If the wire grid comprises a plurality
of parallel rings, the ribbon grid may comprise
a plurality of parallel rings registering with al
ternate spaces between the wire rings.
The circuit associated with the tube shown in
Figure 2 comprises an input circuit 6 connected
between the cathode 2' and the control grid 3',
and an output circuit 1 connected to the anode 5',
the screen being biased by a proper connection to
the source of voltage supply 8,
While we have indicated the preferred embodi
ments of our invention of which we are now
10
15
20
25
aware and have also indicated only one speci?c
application for which our invention may be em
ployed, it will be apparent that our invention is
by no means limited to the exact forms illustrated 30
or the use indicated, but that many variations
may be made in the particular structure used and
the purpose for which it is employed without
departing from the scope of our invention as set
forth in the appended claims.
35
What we claim as new is:
1. An electron discharge device having an en
velope containing a cathode and an anode and
at least two grids between the cathode and an
ode, the grid next to said cathode comprising 40
spaced wires and the grid closer to the anode
comprising spaced ?at members of greater pro
jected area than the Wire members of the grid
next to the cathode, each of said ?at members
registering with a space between two adjacent
45
wire members, and each of the spaces between
the ?at members registering‘ with a space be
tween two adjacent wire members.
2. An electron discharge device having an en
velope containing a cathode and anode, at least
two grids between the cathode and anode, the 50
grid closer to the cathode including a pair of
spaced interspersed helical wires and the grid
closer to the anode including a helical ribbon
grid, the solid portions of the ribbon grid regis
tering with the alternate spaces between the grid
wires, and the space between the turns of the
ribbon grid registering with the other alternate
spaces between the grid wires.
3. An electron discharge device having an en 60
velope containing a cathode and anode, at least
two grids between the cathode and anode, the
grid closer to the cathode comprising a wire grid
of a number of turns and the grid closer to the
anode comprising a ribbon grid of a number of
turns, each turn of the ribbon grid registering 65
with the alternate space between two adjacent
grid wires and the spaces between the turns of
the ribbon grid registering with the other alter
nate spaces between two adjacent grid wires.
70
BERNARDUS DOMINICUS
HUBERTUS TELLEGEN.
MARC ZIEGLER.
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